1. Field of the Invention
This invention relates generally to water pressure regulating devices, and more particularly to systems for dampening water pressure fluctuations in pump systems used to supply fluids to wafer cleaning stations.
2. Description of the Related Art
As is well known, semiconductor devices are fabricated from semiconductor wafers, which are subjected to numerous processing operations. These operations include, for example, impurity implants, gate oxide generation, inter-metal oxide depositions, metallization depositions, photolithography pattering, chemical mechanical polishing (CMP), etc. Although these processes are performed in ultra clean environments, the very nature of many of the process operations is to blame for the generation of surface particles. For instance, when CMP operations are performed, a film of particles and/or metal contaminants are commonly left behind.
Because surface particles can detrimentally impact the performance of an integrated circuit device, wafer cleaning operations have become a standard procedural requirement after certain process steps. Although cleaning operations are rather procedural, the equipment and chemicals implemented to perform the actual cleaning are highly specialized. This specialization is important because each wafer, being at different stages of fabrication, represents a significant investment in terms of raw materials, equipment fabrication time, and associated research and development.
To perform the cleaning operations in an automated manner, fabrication labs typically employ a cleaning system. A typical cleaning system may be, for example, a Synergy(trademark) cleaning system from OnTrak(trademark), of Fremont, Calif., which is a subsidiary of Lam Research Corporation, also of Fremont, Calif. A typical Synergy(trademark) cleaning system employs two brush stations, where each brush station has a set of brushes for cleaning the top and bottom surfaces of a wafer. Each of the brushes are commonly configured to deliver chemicals and DI water Through-The-Brush, to enhance the cleaning ability of the system. The system typically also includes a spin-rinse station, where a wafer, after being cleaned in the brush stations is rinsed with DI water and dried before completing the cleaning cycle.
As can be appreciated, it is very important that facility lines, which supply the DI water to the cleaning system supply the water at substantially steady water pressure levels. Unfortunately, the facility lines in different fabrication labs vary substantially. In some cases, the pressure levels are too high and in others too low. In those cases where the pressure level is too low, laboratory technicians sometimes connect a water pump between the facility lines supplying the DI water and the cleaning system. Although water pumps are able to increase pressure levels, a downside to water pumps is that large pressure fluctuations are also introduced and passed to the cleaning system. In view of the fact that cleaning systems are designed to carefully apply selected amounts of DI water to produce very specific chemical solutions, (i.e., mixture) pressure fluctuations can cause erratic changes in the concentration of applied solutions.
In view of the foregoing, there is a need for pump systems and methods for implementing booster pump systems that minimize the degree of water pressure fluctuations communicated to wafer cleaning systems.
Broadly speaking, the present invention fills these needs by providing a booster pump that can supply water pressure sensitive cleaning systems with a controlled water pressure flow that has a substantial reduction in pulsating water pressure fluctuations. It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, a device, or a method. Several inventive embodiments of the present invention are described below.
In one embodiment, a pressure booster for amplifying a water pressure that is supplied by a water facility is disclosed. The pressure booster includes a pump having a pump input that connects to the water facility and a pump output that is configured to produce a fluctuating amplified water pressure, which is greater than the water pressure that is supplied by the water facility. A pressure dampener having a dampener input for accepting the fluctuating amplified water pressure from the pump output is also included. The pressure dampener is configured to partially reduce pressure fluctuations in the fluctuating amplified water pressure, the pressure dampener also has a dampener output. The pressure booster further includes a pressure regulator having a regulator input for receiving the dampener output. The pressure regulator has a regulator output that is configured to supply a regulated water pressure having a substantially reduced pressure fluctuation. The regulated water pressure is then supplied to a wafer cleaning station, which is configured to perform precision controlled cleaning operations along with other cleaning chemicals.
In another embodiment, a pressure booster for amplifying a water pressure that is supplied by a water facility is disclosed. The pressure booster is configured to be connected between the water facility and one or more semiconductor substrate cleaning systems. The pressure booster includes a pump having a pump input that connects to the water facility and a pump output that is configured to produce a fluctuating amplified water pressure that is greater than the water pressure that is supplied by the water facility. Further included is a pressure dampener having a dampener input for accepting the fluctuating amplified water pressure from the pump output. The pressure dampener is configured to partially reduce pressure fluctuations in the fluctuating amplified water pressure. The pressure dampener also has a dampener output. A pressure regulator having a regulator input for receiving the dampener output is also included as part of the pressure booster. The pressure regulator has a regulator output that is configured to supply an amplified water pressure having a substantially reduced pressure fluctuation, and an adjustment control that is connected to the pressure regulator. The adjustment control is provided to enable precision tuning of the pressure fluctuations at the output of the pressure regulator, such that a substantially more stable water supply can be provided to the cleaning system(s) connected to the pressure booster.
In yet a further embodiment, a method for dampening a fluctuation in water pressure that is configured to be supplied to a wafer cleaning system is disclosed. The method includes: (a) providing a pump for amplifying a pressure level of water received from a facility connection; (b) connecting a pulse dampener to an output of the pump to partially reduce fluctuations in pressure produced by the pump; (c) connecting a pressure regulator to an output of the pressure regulator; (d) monitoring a pressure gauge at an output of the pressure regulator; and (e) adjusting the pressure regulator until an acceptable reduced pressure fluctuation is monitored at the pressure gauge.
Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.